Abstract

This investigation examined the effect of nocturnal use of electronic devices 2 hours prior to bedtime on the quality and quantity of sleep and subsequently on next day performance. Twelve regionalswimmers participated in this work. The randomized and counterbalanced experiment took place over two periods of 5 days each (with smartphone use(S), without smartphone use(S) separated by a week of rest; 3 test sessions were implemented for each period in which 25m and 50m crawl performance (P₂₅ , P₅₀ respectively), oral temperature(T°), and perceived exertion (RPE) were recorded. Simultaneously based on a quantitative research method; quality(SQl) and quantity of sleep(SQt) and symptoms of insomnia (I) were assessed at the beginning and end of each period.All measures were taken in two different times of the day ; morning (07 :00h – 08 :00h) and after noon (18 :00h – 19 :00h).

The results indicated a significant increase in sleep onset latency duration(SL: p<0,05 ;hp²=0,4), and insomnia symptoms( I : p<0,001 ;hp²=0,7) as well as impaired sleep quality (SQl : p<0,05 ;hp²=0,3)associated with elevated temperature(T°: p<0,5 ;hp²=0,3) and perceived exertion (RPE: p<0,05 ; hp²=0,4), under Smartphone conditions. compared to conditions without Smartphone. On the other hand, a significant decrease in physical performance was observed,(P_{25 :}p<0,01 ; hp²=0,5) especially in the morning( at 7:00 a.m:  p<0,05; hp²=0,3) under conditions with Smartphone compared to conditions without Smartphone.

These results suggest that the use of prior to bed may lead to impaired sleep resulting from difficulty falling asleep and mild insomnia. This alteration of sleep caused by exposure to blue light emitted by smartphones explains the increase in temperature, the perceived effort and more importantly the deterioration of swimming performance the next day.

Keywords: physical performance, sleep, Insomnia, Blue light

Tasnim Hidri